Polyethylene oxide (PEO), which is similar in chemical structure to polyethylene glycol (PEG) and polyoxyethylene (POE), is an oligomer or polymer of ethylene oxide. PEG generally refers to oligomers and polymers with a molecular mass below 20,000 g/mol, PEO to polymers with a molecular mass above 20,000 g/mol, and POE to a polymer of any molecular mass.
The state of PEO may depend on its molecular weight, but generally has the following structure:HO—CH2—(CH2—O—CH2—)n—CH2—OH
PEO is often sold or identified under the tradename POLYOX™ as a water-soluble resin. It is advertised as providing binding, thickening, lubricity, water retention, and film formation. It is considered to be a thermoplastic material that is readily calendered, extruded, injection molded, or cast. PEO is used commercially in pharmaceuticals, personal care and cleaning products, mining, building materials, and paper industries in various ways.
PEO has limited solubility in water, but easily drops out of solution. The difficulty in obtaining or maintaining a PEO-water solution is more difficult at higher molecular weight PEO. The table below provides the viscosity of various commercially available POLYOX products by molecular weight. The table below illustrates the difficulty of producing solutions of high PEO content as molecular weight increases. For a 5% (weight) PEO solution in water, the highest commercially feasible molecular weight POLYOX is 900,000. For a 2% (weight) PEO solution in water, the highest commercially feasible molecular weight POLYOX is 2,000,000. For POLYOX having a molecular weight of 7,000,000, commercially feasible weight percent of PEO above 1% are difficult, and in many applications even 1% PEO is not feasible.
POLYOXApprox.Viscosity Range at 25 C., CPNo.MW5% solution2% solution1% solutionWSR N-10100,00030-50WSR N-80200,00055-90WSR N-750300,000  600-1,200WSR-205600,0004,500-8,800WSR-1105900,000 8,000-17,000WSR N-12k1,000,000400-800WSR N-60k2,000,0002,000-4,000WSR-3014,000,0001,6500-5,500 WSR5,000,0005,500-7,500CoagulantWSR-3037,000,000 7,500-10,000
There is a need for improved processes and compositions that enable application of PEO.